Nagios check for systemd failed units

check_systemd_units.sh

#!/bin/bash
# Source http://lzone.de/blog/Nagios+Check+for+Systemd+Failed+Units

# Nagios return codes
STATE_OK=0
STATE_WARNING=1
STATE_CRITICAL=2
STATE_UNKNOWN=3

if [ -f /bin/systemctl ]; then
        failed=$(/bin/systemctl --failed --no-legend | grep -v masked)
        failed=${failed/ */}            # Strip everything after first space
        failed=${failed/.service/}      # Strip .service suffix
        if [ "$failed" != "" ]; then
                echo "CRITICAL: Failed units - $failed"
                exit $STATE_CRITICAL
        else
                echo "OK: No failed units"
                exit $STATE_OK
        fi
else
        echo "UNKNOWN: No systemd. Nothing was checked"
        exit $STATE_UNKNOWN
fi